Artificial lighting systems for closed environments often aim at improving the visual comfort experienced by users. In particular, lighting systems are known which simulate natural lighting, specifically sunlight illumination. The characteristics of the to be imitated outdoor lighting depend on the interaction between the sunlight and the earth atmosphere and create a specific shade characteristic.
EP 2 304 478 A1 and EP 2 304 480 A1, filed by the same applicant, disclose a lighting system with a light source producing visible light, and a panel containing nanoparticles. During operation of the lighting system, the panel receives the light from the light source and acts as a so-called Rayleigh diffuser, namely it diffuses light rays similarly to the earth atmosphere in clear-sky conditions. Specifically, the concept uses directed light with low correlated color temperature (CCT), which corresponds to sunlight and generates shadows in presence of lit objects, and diffused light with larger CCT, which corresponds to the light of the blue sky and, in principal, can generate shadows with a blue tinge.